Ninety-six hour acute toxicity bioassays were employed to
determine the tolerance of juvenile coho salmon to chlorinated
stabilized kraft mill effluent (SKME). In addition the effect of
chlorinated SKME on the growth of juvenile coho salmon in six and
ten day experiments was studied.
Results of the acute toxicity tests...
Between 1982-1984 I studied site tenacity and mate retention in Black Terns at Sycan Marsh, Lake County, Oregon. I banded 778 adult Black Terns and used this marked population to test the hypotheses that site tenacity and mate retention would be less for Black Terns which nest in variable marsh...
Invasion by nonnative brook trout (Salvelinus fontinalis) often results in replacement of bull trout (Salvelinus confluentus) in western North America, but the causal mechanisms are not well understood. Removal of brook trout from 1992 to 2000 from Sun Creek in southern Oregon, provided an opportunity to investigate the changes in...
Listed as endangered in 1988, the Lost River sucker (Deltistes luxatus) and Shortnose sucker (Chasmistes brevirostris) were once abundant and widely distributed in the Klamath Basin in Southern Oregon and Northern California. Populations of both species have been declining since the late 1960’s. Factors thought responsible for declines include naturally...
Anadromous coastal cutthroat trout Oncorhynchus clarkii clarkii may be highly dependent on estuaries, passing through them multiple times during their lifetime. However, few studies have investigated estuarine use by coastal cutthroat trout and it is often thought that estuaries serve primarily as migration corridors rather than rearing areas. We used...
An inextricable link exists between dams and human development in the Pacific Northwest, but they can fragment rivers and reduce genetic connectivity for freshwater and anadromous fishes. Since the early-twentieth century, a series of hydropower and irrigation dams on the mainstem Klamath River, California, has fragmented migratory corridors and eliminated...
Wild populations of fish are faced with a multitude of stressors, which may include human interaction, toxins, and disease. Benzo(a)pyrene (BaP), a known carcinogen and immunotoxin, has been reported in the stomach contents of juvenile chinook salmon, Oncorhynchus tshawytscha, in urban waterways. We investigated the impact of chronic dietary exposure...
The microsporidian parasite Nadelspora canceri infects Dungeness crabs, Cancer magister, along the United States Pacific Northwest coast. The prevalence and seasonal variation of N. canceri in Dungeness crabs from Alsea Bay, Oregon, are described based on examination of 2991 crabs collected at monthly intervals from October, 1991 to June, 1993....
Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may...
Although short-tailed weasels (Mustela erminea) are important predators of small mammals, little is known about their space use, habitat selection, or vulnerability to predation in North America. To evaluate the effects of forest management and social structure on home range size and habitat selection of short-tailed weasels, I conducted a...
The management of small-scale fisheries (SSF) around the world is facing increasing demands for reformation given ecological, social, and economic vulnerabilities. The governance of SSF is particularly important to foster the sustainability of these systems given that it combines regulatory instruments, interactive participation of diverse stakeholders, and the guiding values...
Larval transport and retention of two endangered suckers were studied in a highly
altered lacustrine/riverine complex. The endangered populations of Lost River sucker,
Deltistes luxatus, and shortnose sucker, Chasmistes brevirostris, in Upper Klamath Lake
(UKL), Oregon are the largest remnant populations of these suckers. Downstream of
UKL, the Keno Impoundment...
Rainbow trout (Salmo gairdneri) and bluegill (Lepomis macrochirus)
were exposed to flows of water containing low DO concentrations
produced by bubbling nitrogen through the water. Abrupt exposure of
fish to critical DO concentrations (The standard dose response) and by
a more gradual changing of DO levels (The "stepdown" approach) were...
An estimated 99% of native wet prairie has been lost in the Willamette Valley, Oregon, but a large number of seasonal wetlands remain on private lands dedicated to grass seed production within the historical wet prairie landscape. Because agriculture is known to alter physical and chemical wetland conditions, I investigated...
Declines in populations of anadromous salmonids (Oncorhynchus spp.) in the Columbia River drainage basin have resulted in extensive programs to annually release large numbers of hatchery-raised juvenile salmonids in an effort to support salmonid restoration. The Pacific Flyway population of Caspian terns (Hydroprogne caspia) has grown from around 3,500 nesting...
Rainbow trout were exposed to aluminum at pH 7.25 and
8.25 and four hardnesses (10, 30, 80, and 120 ppm CaCO₃)
for 96 hours in a continuous-flow system and mortality and
aluminum accumulation in the gills were determined.
Temperature, pH, and dissolved oxygen were measured
daily for each treatment. Dissolved...
Two replications of a half dial lei cross experiment were performed among four inbred lines of mosquitofish, Gambusia affinis.
These inbred lines originated from three random-bred stocks: OR,
TX and CD. The experiment was conducted as a completely randomized
design. Experimental material consisted of parental lines and F₁ populations maintained...
The genotype frequencies of one-year-old oyster spat
(Crassostrea gigas) from parents of known genotype, are compared
to the frequencies expected with Mendelian inheritance. The genotypes
are characterized at three enzyme loci, Aspartate amino-transferase
(AAT), Phosphohexose isomerase (PHI) and Leucine
aminopeptidase (LAP), and a general protein locus. In this study
expression...
A static-renewal, seven day test was developed and
utilized to study the effects of nutrition on the sensitivity
of Mysidopsis intii Holmquist to zinc. It was found that
juvenile growth was the most reliable and sensitive endpoint
that could also reflect the subtle effects of low zinc
concentrations and diet...
Historically fire has been the primary disturbance factor in the sagebrush-steppe. The settlement of the West by Euro-Americans, grazing by domestic livestock, and the concomitant spread of invasive species have altered the historical fire regime. Understanding the long-term vegetation structure and fuel succession of the various sagebrush-dominated communities of this...
The Wetland Reserve Program (WRP) is one conservation tool that mitigates national wetland loss and a primary goal for the program includes optimizing wildlife habitat by restoring wetland functions and values. Few studies have evaluated the WRP, which limits our understanding of its impact on wildlife populations. I assessed the...
Rapid adaptation and evolution based on standing genetic variation and novel mutations is likely to be one of the primary ways that species survive the widespread anthropogenic environmental changes expected of the next century. Three-spined stickleback (Gasterosteus aculeatus) are known to be capable of extremely quick, dramatic adaptation in response...
The effects of exposure to suspended silt, kaolin and fuller's
earth on growth and condition of Pacific oysters, 16 months of age,
were studied. The exposure apparatus maintained a continuous flow
of turbid water through chambers containing test oysters. Additional
studies measured the filtration rates of oysters exposed to suspended...
It is critical for wildlife managers to understand the population dynamics of a harvested species, particularly for ungulates, which are a valuable wildlife resource. Due to concerns that mule deer (Odocoileus hemionus) populations in Oregon were declining, more comprehensive data on population vital rates and the factors potentially affecting them...
In the tropics, widespread deforestation and conversion of primary forests to agricultural and pasture lands has resulted in losses of composition, structure, and functions of forest landscapes. Deforestation in the tropics is typically preformed via slash-and-burn practices; the byproducts from combustion have been identified as the second-highest form of anthropogenically...
Coho salmon (Oncorhynchus kisutch) were exposed to sublethal levels of a water-soluble fraction (WSF) of Cook Inlet crude oil for periods ranging from 18 to 31 days, at four acclimation temperatures. The fatty acid composition of phospholipids extracted from muscle, gill, liver, and brain tissues, and, at three of the...
Resident bull trout (Salvelinus confluentus) may be particularly vulnerable to human related disturbance, however very few studies have focused on resident bull trout populations. The abundance of bull trout is one measure of the strength and potential for persistence of a population. Habitat characteristics may influence resident bull trout abundance...
Mule deer (Odocoileus hemionus) populations in south-central Oregon are near their lowest levels since census efforts began in 1961. I investigated fawn survival, cause-specific mortality, and factors contributing to mortality from 2010 – 2012 to identify potential causes for the decline. I also explored pre-parturition and parturition site characteristics.
I...
The fishes of Upper Klamath Lake appeared to distribute
themselves in three general groups during the summers of 1964
and 1965: (1) the chubs--unrestricted as to distribution with slight
seasonal variations; (2) rainbow trout and yellow perch -- restricted
to certain water conditions that exist only along the northern marsh...
I investigated Caspian terns (Sterna caspia) breeding at colonies on the Columbia Plateau (southeastern Washington and northeastern Oregon), with emphasis on the breeding and foraging ecology of Caspian terns nesting at colonies in the mid-Columbia River. I focused research at colonies where Caspian terns foraged on juvenile salmonids (Oncorhynchus spp.)...
This paper lists, and gives individual accounts of, those Oregon mammals that at some time have been referred to as being of a status other than common. Although rare and endangered wildlife species were listed on a national level in the United States, the
large areas of land included in...
This research was designed to evaluate the Fatty Acid Signature (FAS) technique as a non-lethal alternative to more traditional, and sometimes destructive, methods of studying the diet composition of piscivorous birds. Specifically we tested the technique with Caspian terns (Hydroprogne caspia) which currently nest in large numbers in the Columbia...